We were hoping to use the steel roll up doors such as those used in large storage units.

I was also able to get new stainless steel appliances for great prices. 

However, if you're willing to pay that much for it, they'll find a time-slot in their schedule to squeeze you in.You indicated that you've used this guy before, which is probably why he did squeeze you in.While I totally get where you're coming from, it sucks to think you paid too much, this one's on you.

Have your business cards ready, either go in your professional attire, or in your house flipping attire.. we go in our house flipping attire, cargo pants steel boots, smelling like ripe ape.. the women love it.. ahem... and you will be fine.Take the business seriously and have pride calling this YOUR business, and act like it.Show respect and you will be A OK

The biggest value adds we have completed (either for our own or clients properties) are LVT/LVP floors, stainless steel appliances, granite countertops and tile bathrooms. 

Use stainless steel or at least galvanized hardware.

@Steven Steele  We've helped thousands of investors do exactly that, and invest in real estate personally with retirement funds. 

Not that I'd necessarily recommend this, but you could also consider paying down the loan on an accelerated rate (for example, all cashflow goes to principal until paid off), and in that way in short order you two would hold the property and open up your loan slot.  

Dull the finish with steel wool.  

The numbers seem to cash flow really well, and the owner is will to let go of it for what seems like a steel.